The Clinical Assessment of Eccentric and Concentric Stepping Kinetics has Utility in Older African American Men with Knee Arthritis.

Introduction: Stair navigation is physically demanding for individuals with knee osteoarthritis and may result in movement asymmetries that can be quantified using kinetic analysis and force-time parameters. Thus, the purpose of this cross-sectional study was to determine if kinetic force-time parameter asymmetries are present in individuals with knee osteoarthritis and associated with functional outcomes.

Methods: Forty-six older male veterans (61.6±5.6 years) participated. More and less involved legs were defined using the Kellgren and Lawrence (KL) scale and self-reported pain. Kinetics were measured with the Neurocom® Step Up and Over test and quantified with the lift-up index, impact index, movement time, and stair-stepping smoothness. Smoothness was calculated from the level of intermittency in acceleration and deceleration during the concentric and eccentric test movements.

Results: Smoothness was the only force-time parameter to demonstrate an asymmetry. Greater smoothness values were observed for the less-involved leg (p<0.001, 95% CI: 1.22 to 3.64, d=1.17) and were positively associated with gait speed (more-involved: r=0.47, p<0.01; lessinvolved: r=0.53, p<0.01), Knee Injury and Osteoarthritis Outcome Score (KOOS) Symptom (more-involved: r=0.31, p<0.05; less-involved: r=0.39, p<0.01) and ADL (more-involved: r=0.32, p<0.05; less-involved: r=0.39, p<0.05) subscales, and isokinetic knee extension strength (more-involved: r=0.31, p<0.05; less-involved: r=0.42, p<0.01).

Conclusion: Stair-stepping smoothness was diminished in the more involved leg and was associated with worse gait speed, patient-reported outcomes, and knee strength. This observation may reflect compromised motor control associated with decreased strength and greater disease severity in the more-involved leg.